Motor cooling system



G. M. DE JARLAIS MOTOR COOLING SYSTEM Jan. 18, 1949.

2 Shee-tS -Sheet 1 Filed May 15, 1946 IN V EN TOR.

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MOTOR COOLING SYSTEM Filed May 15, 1946 2 Sheets-Sheet 2 Patenited Jan. 18, 1949 MOTOR COOLING SYSTEM Gordon M. De Jarlail, Evansville, Ind., assignmto Seeger Refrigerator Company, a corporation of Minnesota Application May 15, 1948, Serial No. 669,756

Claims. 1

. of refrigeration systems of the type employing a motor compressor.

The present invention relates to an improved system over that covered by the United States patent to James H. Dennedy No. 1,960,576, issued May 29, 1934, on a refrigeration system.

One of the objects of the invention is the provision of an improved motor cooling system which is adapted to provide the most efficient cooling for the motor and compressor of a refrigeration system.

Another object of the invention is the provision of an improved motor cooling system for refrigeration apparatus by means of which the cooling fins on the compressor housing may be eliminated, and the noise level of the apparatus substantially reduced.

Another object of the invention is the provision of an improved refrigeration system with provision for motor and compressor cooling, that is also adapted to produce efilcient oil separation so that oil is kept out of the low side of the system and the efficiency of the system is not reduced by circulating large amounts of oil through the evaporator.

Another object of the invention is the provision of an improved motor compressor construction and motor cooling apparatus in which the motor and compressor have separate housings but the usual housing enclosing the assembly is not requiredand, therefore, the cost of the motor compressor assembly may be substantially reduced.

Still another object of the invention is the provision of an improved cooling system for the motors of refrigeration apparatus which is adapted to utilize eifectively the cooling arrangements'such as the condenser tubes which are provided for this purpose, and in which the cooling effect conforms very closely to the cooling which is required.

Another object of the invention is the provision of an improved refrigeration system which is efficient and in which the motor is adequately cooled and oil returned to the oil reservoir in the motor housing so that the oil which is circulated through the low side of the system is reduced to a minimum.

Another object of the invention is the provision of an improved refrigeration system which is simple, efficient, sturdy, adapted to be manufactured at a low cost, and capable of being used for a long period of time without necessity for repair or replacement or other servicing.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the drawings, of which there are two sheets, 7

Fig. 1 is a diagrammatic elevational view of the refrigeration system;

Fig. 2 is a fragmentary rear elevational view of the cabinet showing a rear view of the removable refrigeration unit; and

Fig. 3 is a side elevational view of the removable refrigeration apparatus shown in partial section and shown in a fragmentary sectional view of the cabinet.

Referring to Fig. 1, the present refrigeration system preferably includes a, motor I0 and a compressor ll driven by the motor, and a condenser I! which utilizes a pair of condenser sections II and It for reducing the vaporized refrigerant to liquid and for cooling the motor.

In the diagrammatic system of Fig. 1, l5 indicates the evaporator, IS the float valve chamber, and the course of the refrigerant through the system is as follows: The outlet from the motor compressor II is connected by conduit H to the inlet part of the condenser section II, which may comprise one or more of the tubes which are thermally connected to the same fins I. as are connected to the main condenser section It.

The outlet end of the tubes of the condenser section 13 is connected by conduit I! to the interior of the motor housing I0, preferably at its upper end. Another conduit 20 leads from the upper end of the motor housing It to the inlet end of the tubes forming the condenser section I4, and the outlet end of these tubes is connected by a conduit 21 to the float valve chamber I.

The discharge opening from the float valve chamber 18 is connected by a conduit 22 to the refrigerant distributing conduit 23 of an evaporator l5, and the vapor headers 24 of the evaporator are connected by a conduit 25 to the inlet of the motor compressor I I.

Referring to Fig. 2, this is a rear elevational view of the actual refrigeration apparatus unit of the type adapted to be mounted in the back of a cabinet in such manner that the motor and compressor are housed partly in the rear wall and partly outside of the cabinet shell. The same numerals have been applied to the parts of this drawing, but the structure is shown in greater detail, and it will be noted that the motor l0 and compressor ll do not require an additional assembly housing enclosing the separate motor and compressor housing.

housing space 32 the velocity of the gas and en- The motor housing is here indicated by the numeral 26 and it is shown in connection with the motor shaft 27, motor 28, shaft bearing 20, stator 30 and windings 3i. The housing 26 of the motor 10 is hermetically sealed'and has a chamber or space 32 at its upper end adjacent the inlet from the conduit i9 and the outlet to the conduit 20.

The operation of the system is as follows: Refrigerant is withdrawn from the evaporator it directly into the compressor cylinder ii through the vapor conduit 25. This permits operation with a minimum heating of the suction gas,as

contrasted with the systems of the prior art in which the suction conduit may lead into an auxiliary housing of the compressor or motor, which housing itself is heated by being in metallic contact with the compressor and motor.

Heating the suction gas before entering the compressor would reduce the density of the gas, which in turn would reduce the capacity of the compressor, and it is desirable to avoid such heating because it would thus reduce the efficiency of the compressor. Therefore, the introduction of refrigerant vapor directly into the cylinder of the compressor permits the compressor to operate more efficiently than it would if the suction gas had been heated and had thus had its density reduced.

The compressed and, therefore, heated vapor is conducted directly out of the compressor Ii by the conduit I] in order to carry away from the compressor and motor, at the earliest opportunity, the heat which has been generated by the compressor. If this heated and compressed gas from the compressor outlet were brought into contact with auxiliary housings of metal which are also connected to the motor, much of this heat might be transmitted by conduction to the motor whereas the present system provides for the carrying away of the heat ofthe compressed vapor at once.

The discharge vapor contains superheated refrigerant gas and a considerable amount of lubricating oil, the latter being in a mist or vapor condition. The discharge vapor is at a relatively high temperature as compared with the temperature of the system.

This discharge vapor from the compressor is conducted by conduit l'l to the inlet portion 13 of the condenser through which it is passed and partially cooled and condensed. In this portion of the condenser the superheat of the refrigerant gas is removed, a portion of the refrigerant gas is condensed to a liquid and is mixed with the lubricating oil which is also now reduced to a liquid condition.

The preliminary cooling of the discharge vapor from the compressor is accomplished under the most efiicient conditions, because it takes place at the highest possible temperature difference, that is, the superheated vapor temperature of approximately 250 F., as compared with the ambient air temperature assumed to be 110 F.

Thus the cooling may be accomplished with the least possible amount of condenser surface. From the condenser section l3 the refrigerant gas is conducted by conduit i9 into the motor housing 26. The conduit I9 carries refrigerant gas at saturation temperature and drops of the liquid oil-refrigerant mixture,-the refrigerant having been only partially liquified.

Emerging from the conduit l9 into the motor trained liquid is greatly reduced because of the enlarged cross-sectional area of the stream in the space 32. This reduction in velocity causes the liquid to drop and the oil refrigerant mixture contacts and cools the motor. The oil runs down through the windings to the oil sump. Therefore, no separate cooling or oil separation system is required.

As described in the prior patent to James H. Dennedy, to which reference is made on page 1, a suitable conduit (not shown) isprovided for conducting oil from the oil sump at the base oi the motor housing back to the compressor inlet.

The liquid refrigerant partially condensed in the condenser section It is vaporized by contact with the heated motor parts, cooling the motor very eflectively by utilizing heat of the motor to evaporate the liquid refrigerant.

The refrigerant vapor from the space 32 of the motor housing, containing practically no oil, is then conducted from the housing through the conduit 20 to the main or second section it of the condenser l2. Here the refrigerant is condensed and its flow being regulated by the float valve chamber in the chamber IS the refrigerant again enters the evaporator i5.

Various types of evaporators may be employed, the one selected for illustration having a refrigerant distributing conduit at the bottom, a multiplicity of conduits extending upwardly on both sides between sheets of metal and headers 24 at the top. The suction pipe 25 is connected to the headers 24.

It has been found that where a relatively large cooling effect is required the present system conforms to the requirement, and where a relatively small cooling efiect is required the system also conforms to the cooling requirement under these conditions. For example, if the system were operating under rather adverse conditions at 110 F. ambient temperature and 30 pounds per square inch suction pressure, the hot gas at approximately 250 F. is superheated approximately 100 F. as it is discharged from the compressor to the first condenser section The saturated vapor-oil refrigerant mixture enters the motor housing and is again heated so that on leaving the housing thetemperature may be approximately 200 F. or F. superheat.

At low ambient temperatures, such as F. to

70 F., there is a somewhat larger amount of refrigerant in the oil which cools the compressor cylinder. The resulting discharged vapor carries less superheat than is encountered in the case of adverse conditions. On passing through the housing, the refrigerant picks up very little superheat (4 F. to 8 F.).

Thus where a relatively large cooling eifect is required, it is provided by this system and where a relatively small cooling effect is required the system conforms to this requirement.

It will thus be observed that I have invented an improved cooling system adapted to cool the motor and compressor of a refrigeration apparatus very eiiiciently, while separating the oil and keeping the oil out of the evaporator, thus increasing the emciency of the entire refrigeration system.

The present motor cooling system is very eflicient in regard to condenser area as it operates at a maximum temperature difierence. No sepa The present system eliminates the necessity for cooling fins n the compressor housing and the precise details of construction set forth, but

desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I- claim as new and desire to secure by Letters Patent of the United States, is:

l. The method of refrigeration which comprises withdrawing vapor from an evaporator directly into a compressor located outside of a motor housing, compressing the vapor and discharging the superheated and compressed vapor directly from the compressor into a preliminary cooling condenser, partially condensing the vapor and consolidating the oil entrained therewith into droplets in said condenser and conducting the partially condensed vapor and oil from the condenser into an upper part of the housing of a motor driving said compressor and having a housing separate from said compressor, causing vthe condensed liquid refrigerant and oil to run down in the motor housing to cool the motor parts, the refrigerant again evaporating in this cooling operation, and the oil being separated and collected in an oil sump, and discharging the vapor substantially without oil from the top of the motor housing into a main condenser, where it is cooled and liquefied for use in the evaporator.

2. The method of refrigeration which comprises withdrawing vapor from an evaporator directly into a compressor located outside of a motor housing, compressing the vapor and discharging the superheated and compressed vapor directly from the compressor into a preliminary cooling condenser, partially condensing the vapor and consolidating the oil entrained therewith into droplets in said condenser and conducting the partially condensed vapor and oil from the condenser into an upper part of the housing of a motor driving said compressor and having a housing separate from said compressor, causing the condensed liquid refrigerant and oil to run down in the motor housing to cool the motor parts, the refrigerant again evaporating in this cooling operation, and the oil being separated and collected in an oil sump, and discharging the vapor substantially without oil from the top of the motor housing into a main condenser, where it is cooled and liquefied for use in the evaporator, and cooling the external parts of the motor housing and the compressor housing and removing the heat radiated therefrom by passing a current of air upward from the said condensers.

3. In a refrigeration system, a motor compressor assembly comprising a motor having a separate housing and a compressor having a separate housing, these housings being located adjacent each other, and the motor having a shaft extending into the compressor, an evaporator having its suction side directly connected to the inlet of said compressor, a preliminary cooling condenser having its inlet connected directly to the outlet of the compressor, whereby the superheated and compressed gas is carried away from the compressor without said gas passing through the motor housing, the outlet of said preliminary condenser being connected to the top of the motor housing, and said preliminary condenser having a predetermined heat exchange area to condense partially the refrigerant vapor and consolidate the entrained oil into droplets, the partially condensed refrigerant and oil running down on the motor parts inside the motor housing, and the partially condensed vapor effecting a cooling of said motor parts with a resultant revaporization of the refrigerant in the motor housing, the oil collecting in a sump in the lower part of the motor housing to separate the oil from the refrigerant, a main condenser having a predetermined heat exchange area to cool and liquefy the refrigerant vapor received from the motor housing the said motor housing having another conduit connecting its upper part with said main condenser, and conduit means connecting said main condenser with the evaporator.

4. In a refrigeration system, a motor compressor assembly comprising a motor having a separate housing and a compressor having a separate housing, these housings being located adjacent each other, and the motor having a shaft extending into the compressor, an evaporator having its suction side directly connected to the inlet of said compressor, a preliminary cooling condenser having its inlet connected directly to the outlet of the compressor, whereby the superheated and compressed gas is carried away from the compressor without said gas passing through the motor housing, the outlet of said preliminary condenser being connected to the top of the motor housing, and said preliminary condenser having a predetermined heat exchange area to condense partially the refrigerant vapor and consolidate the entrained oil into droplets, the partially condensed refrigerant and oil running down on the motor parts inside the motor housing, and the partially condensed vapor effecting a cooling of said motor parts with a resultant revaporization of the refrigerant in the motor housing, the oil collecting in a sump in the lower part of the motor housing to separate the oil from the refrigerant, a main condenser having a predetermined heat exchange area to cool and liquefy the refrigerant vapor received from the motor housing the said motor housing having another conduit connecting its upper part with said main condenser, and conduit means connecting said main condenser with the evaporator, the amount of cooling effect of said system on the motor and compressor being determined by the ambient temperature in which the system operates so that there is a greater cooling effect, as required, when the system is operating in a higher ambient temperature.

5. In a refrigeration system, a motor compressor assembly comprising a motor having a separate housing and a compressor having a separate housing, these housings being located adjacent each other, and the motor having a shaft extending into the compressor, an evaporator having its suction side directly connected to the inlet of said compressor, a preliminary cooling condenser having its inlet connected directly to the outlet of the compressor, whereby the superheated and compressed gas is carried away from the compressor without said gas passing through the motor housing, the outlet of said preliminary condenser being connected to the top of the motor housing, and said preliminary condenser having a predetermined heat. exchange area to condense.

vapor received from the motor housing the said motor housing having another conduit connecting its upper part with said main condenser, and conduit means connecting said main condenser with the evaporator, the said main condenser section including a heat exchange area many times that of the preliminary condenser, and the said condensers being located below the motor and compressor in the stream of air passing upward about the motor and compressor.

GORDON M. DE JARLAIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,898,438 Greenwald Feb. 21, 1933 2,420,442

Rataiczak May 13, 1947 

